feat: add colored due date indicators to list and show views

- List view: show relative due date (+12d, -3d, today) after namespace
- Show view: colorize full due date based on urgency
- Color scheme: red (overdue), yellow (due within 3 days), green (4+ days)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/cmd/output.go

@@ -7,8 +7,10 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"math"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/fatih/color"
 )
@@ -89,13 +91,14 @@ func PrintNodes(w io.Writer, svc service.NodeService, nodes []*models.Node, json
 			}
 			ns_rel_node_titles = append(ns_rel_node_titles, ns_rel_node.Title)
 		}
-		fmt.Fprintf(w, "  %s %s %s %s %s %s",
+		fmt.Fprintf(w, "  %s %s %s %s %s %s %s",
 			cDim.Sprint(n.ID),
 			render(prioRM, n.GetProperty("prio"), true),
 			render(statusRM, n.GetProperty("status"), true),
 			render(typeRM, n.GetProperty("type"), true),
 			cTitle.Sprint(truncate(n.Title, 80)),
 			cDim.Sprint("["+strings.Join(ns_rel_node_titles, ",")+"]"),
+			dueDateShort(n.DueDate),
 		)
 		tags := n.GetDisplayTags()
 		if len(tags) > 0 {
@@ -117,7 +120,7 @@ func PrintNode(w io.Writer, svc service.NodeService, n *models.Node, jsonOut boo
 	fmt.Fprintf(w, "  Status:    %s\n", render(statusRM, n.GetProperty("status"), false))
 	fmt.Fprintf(w, "  Priority:  %s\n", render(prioRM, n.GetProperty("prio"), false))
 	if n.DueDate != nil {
-		fmt.Fprintf(w, "  Due:       %s %s\n", iconCalendar, n.DueDate.Format("2006-01-02"))
+		fmt.Fprintf(w, "  Due:       %s\n", dueDateLong(n.DueDate))
 	}
 	fmt.Fprintf(w, "  Created:   %s\n", cDim.Sprint(n.CreatedAt))
 	fmt.Fprintf(w, "  Updated:   %s\n", cDim.Sprint(n.UpdatedAt))
@@ -202,6 +205,57 @@ func render(rm RenderMap, key string, short bool) string {
 	return v.c.Sprint(v.l)
 }
 
+// dueDateShort returns a "+12d" / "-3d" style string colored by urgency.
+func dueDateShort(d *models.Date) string {
+	if d == nil {
+		return ""
+	}
+	now := time.Now().UTC().Truncate(24 * time.Hour)
+	due := d.UTC().Truncate(24 * time.Hour)
+	days := int(math.Round(due.Sub(now).Hours() / 24))
+
+	var label string
+	if days == 0 {
+		label = "today"
+	} else if days > 0 {
+		label = fmt.Sprintf("+%dd", days)
+	} else {
+		label = fmt.Sprintf("%dd", days)
+	}
+
+	var c *color.Color
+	switch {
+	case days < 0:
+		c = cBad
+	case days <= 3:
+		c = cWarn
+	default:
+		c = cGood
+	}
+	return c.Sprint(label)
+}
+
+// dueDateLong returns the full date string colored by urgency.
+func dueDateLong(d *models.Date) string {
+	if d == nil {
+		return ""
+	}
+	now := time.Now().UTC().Truncate(24 * time.Hour)
+	due := d.UTC().Truncate(24 * time.Hour)
+	days := int(math.Round(due.Sub(now).Hours() / 24))
+
+	var c *color.Color
+	switch {
+	case days < 0:
+		c = cBad
+	case days <= 3:
+		c = cWarn
+	default:
+		c = cGood
+	}
+	return c.Sprintf("%s %s", iconCalendar, d.Format("2006-01-02"))
+}
+
 func truncate(s string, max int) string {
 	if len(s) <= max {
 		return s